The present invention relates to a taping unit in a sealing machine for cardboard boxes, equipped with a control system for signalling the absence of tape for sealing the boxes.
As is well known, taping machines for sealing cardboard boxes include a bed with means for advancing the boxes as well as taping units for applying a strip of tape to the top and to the bottom of the box.
Each taping unit (see, for example, application No. 23191 A/84 by the same applicant) is equipped with a support roller for the roll of adhesive tape, other support rollers for the tape and rollers for applying the tape on the box. Said rollers for applying the tape are inserted on pivots fixed to arms which are elastically movable to follow the contour of the moving box and press the applied tape to it. The tape is unwound from the roll by the movement of the box and is cut at an appropriate distance by means of a cutting member which operates after the rear end of the box has passed a certain point.
If the tape breaks at any point along its path, the box which is passing the taping machine at that instant will be only partially sealed while the subsequent boxes will not be sealed at all. It is therefore necessary to act promptly by stopping the machine and restoring its correct operation.
It follows that there will be a loss of time and an additional inconvenience for the operator because the boxes which have already passed the machine without being sealed must be taken back upstream from the taping machine.
The same defect occurs when the roll of tape finishes or with any other problem connected with the tape feed.